This invention relates to a mineral mining installation, and in particular to a mineral mining installation for winning material along the entire length of a longwall working.
Longwall workings are usually won by a winning machine (such as a plough) which is movable to and fro along a guide fixed to the face side of a scraper-chain conveyor. The conveyor usually extends practically the entire length of the longwall face, and has bulky drive stations (for both the conveyor and the winning machine) at its ends. These drive stations inevitably occupy a large amount of space at the ends of the working, and effectively prevent the winning machine from winning material in the end (stable-hole) regions of the longwall face. These stable-hole regions must, therefore, be won separately; and this can be done either manually, or by the use of auxiliary (stable-hole) winning machines. Both of these courses are undesirable, as they require extra effort and/or equipment. Moreover, because of the congestion in these regions (which arises from the positioning of the bulky drive stations), there are difficulties in the actual winning of material in the stable-hole regions.
One way of getting round these difficulties is to have a longwall conveyor which has curved conveyor sections at each end, the curved conveyor sections leading to conveyor portions situated in the roadways at the two ends of the longwall working. In this case, the guide at the face side of the conveyor can extend the entire length of the longwall face, so that a single winning machine can win material even in the stable-hole regions. Moreover, the drive stations for the conveyor can be positioned in the roadways, so that congestion of the ends of the longwall working is reduced. The scraper assembly of such a conveyor is guided round each of the curved conveyor sections by a respective guide assembly constituted by a pair of pulley wheels which are independently rotatably mounted on a vertical axle radially inward of the respective curved conveyor section. One pulley wheel guides the scraper assembly in the upper (conveying) run, and the other pulley wheel guides the scraper assembly in the lower (return) run. Usually, the pulley wheels guide the scraper assembly by engagement with the radially-inner ends of the scrapers.
Although this arrangement does reduce the congestion at the ends of the longwall working, whilst permitting the entire longwall face to be won by a single winning machine, there is still a certain amount of congestion in the stable-hole regions. This arises because the drive stations for the winning machine extend, at least partially, across the longwall working. Although this may not be too much of a problem for normal longwall working, it is extremely disadvantageous for so-called retreating longwall working (that is to say where the two roadways are driven their entire length to the far end of a seam, and the seam is then won in strips, back along the roadways). This is because the roof of the mine in the regions where the longwall working merges with the roadways need to be adequately supported, and roof support units of the type which support the rest of the longwall working cannot fulfil this function because they are too large to fit in the restricted areas at the ends of the working.
The aim of the invention is to provide a longwall mineral mining installation that is capable of winning the entire longwall face using a single winning machine, and which can be used for both retreating and normal working.